1. Field of the Invention
The present invention relates to a multi-core optical fiber and a method of producing the same.
2. Related Background Art
As an optical fiber acceptable to high density packaging or diameter-reducing of the optical cable, great attention is being focused on the use of a multi-core optical fiber (MCF) in which plural cores are housed in a single fiber. For example, a multi-core optical fiber with various shapes is disclosed in Japanese Patent Application Laid-Open No. H10-104443 (Patent Document 1). Such a multi-core optical fiber assumes mutual connection between multi-core optical fibers or connection to an optical integrated device. As another example of a multi-core optical fiber, for example, Japanese Patent Application Laid-Open No. S62-144110 (Patent Document 2) and Japanese Patent Application Laid-Open No. 2003-201140 (Patent Document 3) disclose an example of manufacturing multi-core fiber by assembling the plurality of preforms by using the assembling glass medium at the center of the glass preform. The assembled preform is drawn into multi-core fiber by applying coatings at the outer portion of the glass fiber, in addition to a directional coupler that is used by directly connecting plural single-core optical fibers to one end of the multi-core optical fiber.